Firearm Basics

Step 1: Knowledge of Firearms

In order for you to join our investigation, you must first prove that you have a basic understanding of firearms and the appropriate nomenclature. Your first assignment is to create a set of flashcards with the following terms:

Barrel

Bore

Breechblock

Bullet

Caliber

Cartridge

Ejector

Extractor

Gauge

Grooves

Lands

Primer

Projectile

Revolver

Rifling

Semiautomatic

Shell

Slide

Striations

Toolmark

Read through the information below to build your knowledge of firearms. Create a Jeopardy-styled slide show and share it with your teacher.

Types of Firearms

While there are many types of firearms, for the purpose of this assignment we are going to classify them into three main categories: handguns, rifles, and shotguns.

Handguns

Handguns can be fired with one hand and typically have a barrel less than 16 inches. Handguns can be further classified into two groups: revolvers and semiautomatic pistols. Both semiautomatic pistols and revolvers require a separate pull of the trigger for each shot fired. The primary difference between the two is that semiautomatic pistols eject the fired cartridge after each shot while the fired cartridge remains inside the cylinder of a revolver. There are also double action revolvers where the pull of the trigger cocks and releases the hammer.

Semi-automatic pistols eject fired cartridges after each shot.

Fired cartridges must be manually removed from revolvers.

Rifles

Rifles are fired with two hands and are typically braced against the shoulder. The barrels of rifles are longer than 16 inches and the projectile is fired with each pull of the trigger. Rifles get their name through the rifling process, which adds spin and accuracy to the projectiles. Rifles are are usually grouped as bolt-action or semiautomatic, but can also be lever-action, slide/pump action or top-break.

Semiautomatic rifle

Bolt-action rifle

Lever-action rifle

Pump-action rifle

Shotguns

Shotguns have smooth barrels (no rifling) and have a wide variety of ammunition. Instead of cartridges and bullets, shotguns use shells which are usually filled with pellets. Having barrels over 18 inches, shotguns are fired using both hands and the stock is usually braced against the shoulder. The two most common shotguns designs are pump action or semi-automatic. Pump action shotguns require the user to physically move the pump handle to re-chamber the next shell while ejected the old one.

A pump-action shotgun requires moving the pump handle to chamber the next shell.

Semi-automatic shotguns rely on recoil or gas to chamber the next shell.

Firearm Components

While there are many types of firearms, most of them have the same basic components.

External Components

The basic external components of a semiautomatic pistol

The basic external components of a revolver

The basic internal components of a semiautomatic pistol

Internal Components

The breechface is the area of the slide the where the cartridge rests before firing.

The function of the ejector is to kick the fired cartridge from the firearm when the slide is moving backwards.

The firing pin aperture is a small opening in which the firing pin passes through. The firing pin is hit by the hammer to fire the cartridge.

The extractor serves as a hook designed to grab the cartridge case and pull it from the barrel after firing.

Fired cartridges of revolvers must be manually removed which means revolvers do not have extractors or ejectors.

Manufacturing Components

All surfaces of firearms are machined during the manufacturing process. The machining process leaves marks which are specific to that particular method. For example, the flat parts of a firearm are created using something called an endmill, which results in leaving circular marks on the surface. The round parts of a firearm are created using a lathe, which also results in characteristic marks left on the surface of the firearm. These marks are appropriated called toolmarks and can be rough enough to be seen with the naked eye or may be smoother, requiring the aid of a microscope.

Endmills can cut with either side or the end

The resulting toolmarks left behind from an endmill

A lathe is used to manufacture round firearm components

A round firearm component with resulting toolmarks

Manufacturing the Barrel

Rifling is the process of cutting spiral grooves in the bore of the barrel of a firearm. The purpose of rifling a barrel is to add accuracy and longevity to the bullet once it has been fired. It is the same concept as throwing a spiral pass when throwing a football--the ball is more accurate and stays in the air longer. There are various techniques to rifling a barrel, including broach cutting, button rifling, and hammer forging. Despite the method being used, the end result is that bore of the barrel has raised areas called lands, and lowered areas called grooves. Additionally, the direction of the spiral may be clockwise or counter-clockwise, depending on the preference of the gun manufacturer.

The diameter of the bore determines the caliber of the firearm. The caliber can be measured in either metric or English units. A common metric caliber is 9mm. Common English calibers refer to width of the bore in inches, such as .22, .45, .357.

Gauge is a measure of bore diameter for shotguns. Gauge is determined from the weight of a solids sphere of lead that will fit the bore of the firearm. It dates back to the use of cannons. The 12-gauge is the most common shotgun.

Ammunition

Different types of firearms require different ammunition. Unfired ammunition of handguns and rifles are called cartridges, while the ammunition of shotguns are called shells.

Cartridges

Although most people refer the ammunition of handguns and rifles as bullets, the bullet is only one component of the cartridge. There are actually four components of a cartridge:

Bullet - bullets are also called projectiles and typically made of lead and a "jacket" made of copper. Other materials include zinc, brass, or alloys.
Gun Powder - the gun powder is also knows as the propellant. When the gun powder burns it produces a large expansion of gas, which is actually what pushes the bullet through the barrel.
Cartridge Case - typically made of brass but can also be plated with nickel or made from aluminum. The cartridge case contains all other components. Numerals, letters and symbols are often stamped into the head of the cartridge case or shotgun shell to identify the manufacturer, caliber, gauge, or to give additional information. These stamps are called headstamps.
Primer - the primer contains shock-sensitive explosive that is placed in the cartridge at the factory. The explosive sparks when it is struck by the firing pin causing the gun powder to ignite.

Different Types of Bullets

Full Metal Jacket

Jacketed Hollow Point

Jacketed Soft Point

Boat Tail

Shotgun Shells

All shotgun shells are typically constructed of the same basic components but may vary in the type of projectiles being used. For example, bird shot is comprised of small pellets, while buckshot is made of large pellets. Slugs are solid projectiles designed to be similar to a bullet fired from a rifle. Shotgun bores are measured using

The main components of shotgun shells

Birdshot (left) compared to buckshot (right)

Assignment #1 - Firearm Vocabulary

Now that you have had a chance to read through the basics of firearms, your first assignment is to create a Jeopardy-styled review game to prepare for the quiz. We are going to use this Google Slides template Firearms Vocabulary Jeopardy to create the game. You will need to be signed into your FCS Google account to proceed. Be sure to share your Google Sheet with your teacher using the following naming convention: Period#.FirearmVocabulary.FirstName.LastName.